IOS Xcode crash only when connected to Xcode

I'm getting intermittent crashes with my app when testing witch my device connected to Xcode. I'f I play the same build not connected to Xcode I don't crash.

in xcode I will randomly get a null reference exception filename unknown. but the strangest part is the function it looks like the null reference is coming from is a script that isn't even in the active scene.

Unhandled Exception: System.NullReferenceException: A null value was found where an object instance was required. at bubbleCollision..ctor () [0x00000] in :0

bubbleCollision is a C# file in my app but is not attached to any objects in the scene.

Any ideas how to track this down?